When booting into the ISO, Make sure that you select the '''Alternate 64 bit kernel (altker64)'''. The ZFS modules have been built specifically for this kernel rather than the standard kernel.

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{{fancywarning|'''When booting into the ISO, Make sure that you select the "Alternate 64 bit kernel (altker64)". The ZFS modules have been built specifically for this kernel rather than the standard kernel. If you select a different kernel, you will get a fail to load module stack error message.'''}}

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{{fancywarning|'''If you select a different kernel, you will get a fail to load module stack error message.'''}}

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== Creating partitions ==

== Creating partitions ==

Revision as of 19:26, March 4, 2014

Introduction

This tutorial will show you how to install Funtoo on ZFS (rootfs). This tutorial is meant to be an "overlay" over the Regular Funtoo Installation. Follow the normal installation and only use this guide for steps 2, 3, and 8.

Introduction to ZFS

Since ZFS is a new technology for Linux, it can be helpful to understand some of its benefits, particularly in comparison to BTRFS, another popular next-generation Linux filesystem:

On Linux, the ZFS code can be updated independently of the kernel to obtain the latest fixes. btrfs is exclusive to Linux and you need to build the latest kernel sources to get the latest fixes.

ZFS is supported on multiple platforms. The platforms with the best support are Solaris, FreeBSD and Linux. Other platforms with varying degrees of support are NetBSD, Mac OS X and Windows. btrfs is exclusive to Linux.

ZFS has the Adaptive Replacement Cache replacement algorithm while btrfs uses the Linux kernel's Last Recently Used replacement algorithm. The former often has an overwhelmingly superior hit rate, which means fewer disk accesses.

ZFS has the ZFS Intent Log and SLOG devices, which accelerates small synchronous write performance.

ZFS handles internal fragmentation gracefully, such that you can fill it until 100%. Internal fragmentation in btrfs can make btrfs think it is full at 10%. Btrfs has no automatic rebalancing code, so it requires a manual rebalance to correct it.

ZFS has raidz, which is like RAID 5/6 (or a hypothetical RAID 7 that supports 3 parity disks), except it does not suffer from the RAID write hole issue thanks to its use of CoW and a variable stripe size. btrfs gained integrated RAID 5/6 functionality in Linux 3.9. However, its implementation uses a stripe cache that can only partially mitigate the effect of the RAID write hole.

ZFS supports data deduplication, which is a memory hog and only works well for specialized workloads. btrfs has no equivalent.

ZFS datasets have a hierarchical namespace while btrfs subvolumes have a flat namespace.

ZFS has the ability to create virtual block devices called zvols in its namespace. btrfs has no equivalent and must rely on the loop device for this functionality, which is cumbersome.

The only area where btrfs is ahead of ZFS is in the area of small file
efficiency. btrfs supports a feature called block suballocation, which
enables it to store small files far more efficiently than ZFS. It is
possible to use another filesystem (e.g. reiserfs) on top of a ZFS zvol
to obtain similar benefits (with arguably better data integrity) when
dealing with many small files (e.g. the portage tree).

Disclaimers

Warning

This guide is a work in progress. Expect some quirks.

Important

Since ZFS was really designed for 64 bit systems, we are only recommending and supporting 64 bit platforms and installations. We will not be supporting 32 bit platforms!

Video Tutorial

As a companion to the installation instructions below, a YouTube video tutorial is now available:

Important

The video and guide are currently out of sync. The video has newer instructions. The guide needs to be updated.

Downloading the ISO (With ZFS)

In order for us to install Funtoo on ZFS, you will need an environment that already provides the ZFS tools. Therefore we will download a customized version of System Rescue CD with ZFS included.

Booting the ISO

Warning

When booting into the ISO, Make sure that you select the "Alternate 64 bit kernel (altker64)". The ZFS modules have been built specifically for this kernel rather than the standard kernel. If you select a different kernel, you will get a fail to load module stack error message.

Creating partitions

There are two ways to partition your disk: You can use your entire drive and let ZFS automatically partition it for you, or you can do it manually.

We will be showing you how to partition it manually because if you partition it manually you get to create your own layout, you get to have your own separate /boot partition (Which is nice since not every bootloader supports booting from ZFS pools), and you get to boot into RAID10, RAID5 (RAIDZ) pools and any other layouts due to you having a separate /boot partition.

gdisk (GPT Style)

A Fresh Start:

First lets make sure that the disk is completely wiped from any previous disk labels and partitions.
We will also assume that /dev/sda is the target drive.

# gdisk /dev/sda
Command: x ↵
Expert command: z ↵
About to wipe out GPT on /dev/sda. Proceed?: y ↵
GPT data structures destroyed! You may now partition the disk using fdisk or other utilities.
Blank out MBR?: y ↵

Warning

This is a destructive operation. Make sure you really don't want anything on this disk.

If you are using encrypted root, change /dev/sda3 to /dev/mapper/vault_1.

Note

ashift=12 should be use if you have a newer, advanced format disk that has a sector size of 4096 bytes. If you have an older disk with 512 byte sectors, you should use ashift=9 or don't add the option for auto detection.

Note

If you have a previous pool that you would like to import, you can do a: zpool import -f -R /mnt/funtoo <pool_name>.

Create the zfs datasets

We will now create some datasets. For this installation, we will create a small but future proof amount of datasets. We will have a dataset for the OS (/), and your swap. We will also show you how to create some optional datasets: /home, /var, /usr/src, and /usr/portage.

Add filesystems to /etc/fstab

Before we continue to compile and or install our kernel in the next step, we will edit the /etc/fstab file because if we decide to install our kernel through portage, portage will need to know where is your /boot so that it can place the files in there. We also need to update /etc/mtab so our system knows what is mounted. Edit /etc/fstab:

Kernel Configuration

To speed up this step, you can install "bliss-kernel" since it's already properly configured for ZFS and a lot of other configurations. The kernel is also compiled and ready to go. To install sys-kernel/bliss-kernel (package not on wiki - please add) type the following:

# emerge bliss-kernel

Now make sure that your /usr/src/linux symlink is pointing to this kernel by typing the following:

<kernel_name> is the name of what you selected in the initramfs creator, and the name of the outputted file.

Using boot-update

/boot on separate partition

If you created a separate non-zfs partition for boot then configuring boot-update is almost exactly the same as a normal install except that auto detection for root does not work. You must tell boot-update what your root is.

Genkernel

If your using genkernel you must add 'real_root=ZFS=<root>' and 'dozfs' to your params.
Example entry for /etc/boot.conf:

Bliss Initramfs Creator

If you used the Bliss Initramfs Creator then all you need to do is add 'root=<root>' to your params.
Example entry for /etc/boot.conf:

"Funtoo ZFS" {
kernel vmlinuz[-v]
initrd initrd[-v]
params root=tank/os/funtoo/root quiet
# If you have an encrypted device with a regular passphrase,
# you can add the following line
params += enc_root=/dev/sda3 enc_type=pass
}

After editing /etc/boot.conf, you just need to run boot-update to update grub.cfg

# boot-update

/boot on ZFS

TBC - pending update to boot-update to support this

Final configuration

Add the zfs tools to openrc

# rc-update add zfs boot

Clean up and reboot

We are almost done, we are just going to clean up, set our root password, and unmount whatever we mounted and get out.

Delete the stage3 tarball that you downloaded earlier so it doesn't take up space.
# cd /
# rm stage3-latest.tar.xz
Set your root password
# passwd
>> Enter your password, you won't see what you are writing (for security reasons), but it is there!
Get out of the chroot environment
# exit
Unmount all the kernel filesystem stuff and boot (if you have a separate /boot)
# umount -l proc dev sys boot
Turn off the swap
# swapoff /dev/zvol/tank/swap
Export the zpool
# cd /
# zpool export tank
Reboot
# reboot

Important

Don't forget to set your root password as stated above before exiting chroot and rebooting. If you don't set the root password, you won't be able to log into your new system.

and that should be enough to get your system to boot on ZFS.

After reboot

Create initial ZFS Snapshot

Continue to set up anything you need in terms of /etc configurations. Once you have everything the way you like it, take a snapshot of your system. You will be using this snapshot to revert back to this state if anything ever happens to your system down the road. The snapshots are cheap, and almost instant.

To take the snapshot of your system, type the following:

# zfs snapshot -r tank@install

To see if your snapshot was taken, type:

# zfs list -t snapshot

If your machine ever fails and you need to get back to this state, just type (This will only revert your / dataset while keeping the rest of your data intact):

# zfs rollback tank/os/funtoo/root@install

Important

For a detailed overview, presentation of ZFS' capabilities, as well as usage examples, please refer to the ZFS Fun page.